Diagram 1As shown in the diagram on the left, each cluster is assigned SAT
at different frequencies. There are three different frequencies. They are
5970Hz(SAT 1),6000Hz(SAT 2) and 6030Hz(SAT 3).

The base station of a cell would first send this SAT to the mobile phone when it enters this cell.
After the mobile phone receives this SAT, it would re-transmit this SAT almost
continuously to the base station. So any co-channel interference would be sensed as it would carry the wrong SAT
frequency. In this case the unknown person's mobile phone would be
transmitting the wrong SAT to Grommit's current base station. The base station can then mute the unknown
user's conversation.

III is correct
Cells using the same channel frequency would be located in different clusters. So, increasing the
size of the clusters would cause these cells using the same channel frequency to be further away
from each other. Therefore co-channel interference is reduced.III is not an extremely accurate answer unlike II, but it is an acceptable answer owing to the
fact that cluster size plays a major role in the degree of co-channel interference in both analogue and digital cellular networks.

IV is incorrect
Increasing the bandwidth can only make matters worst as it reduces the number of different channel frequencies. So, the same channel
frequency would be re-used in cells that are closer together.

The two circle area which overlaps shows the handover area. The mobile phone reaches this circle when it arrives at the handover threshold point[t0] and leaves this
area when it reaches the receiver threshold point[t1].

The handover threshold is set at the point where the power received from a
neighbouring cell site has started to exceed the power received from the current BS
for certain amount and/or for a certain time.
The receiver threshold is the point at which the received power from the BS is at
the minimum acceptable level.
A main requirement here in order to prevent forced termination of a call is that :-

The mobile phone must be assigned a new Base Station(thus the relevant channels needed to continue a call) within the time interval (t1 - t0).

If queuing of handover request is done within the time interval (t1 - t0), the above mentioned condition will be satisfied.
This is why queuing of handover request is possible.